The bicycle is widely used in many countries foreign to the United States as a means of personal transportation. It is also widely used in the United States primarily by students and others who have only a short distance to travel. In recent years, the bicycle has developed into a fairly standard configuration. It has a rigid frame which is made as light as possible consistent with durability and cost of manufacture, for each particular style of riding. Creative design has been somewhat limited by the fact that the bicycle racing authorities do not permit innovative bicycles to be raced in sanctioned races. New materials have opened up new design opportunities, but until recently, there has been little significant change in bicycle design.